Part of Simi Valley Due 11% Water Rate Hike : Utilities: PUC approves increase to help offset boost imposed by suppliers last year. New levels go into effect Monday.

Water rates for one-third of Simi Valley's residents will jump by as much as 11.7% starting Monday, a private water distributor has announced.

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Southern California Water Co. has gained approval from the state Public Utilities Commission to hike its rates to help offset increases made by its suppliers last year, said Dan Dell'Osa, the company's tariff manager.

The average residential bill will climb about 11%, from $388.44 to $430.56 annually. Customers with larger bills will see a slightly bigger increase.

The company made its last rate hike of 12.7% in October, 1992.

Both increases were made to cover the rising price of water, Dell'Osa said.

"It costs us more to buy the water, so we have to make up for that by charging more when we sell it," Dell'Osa said.

Southern California Water buys its water from the Calleguas Municipal Water District, the largest supplier in Ventura County, which in turn taps into reservoirs owned by the Metropolitan Water District of Southern California.

MWD earlier this month announced its fourth annual rate hike, upping rates by 7%, and compelling Calleguas and local water distributors to absorb the additional cost or pass it on to their customers.

Calleguas board members will meet March 30 to decide whether to pass MWD's increase on to its customers.

"We're ironing out the details right now," said Don Kendall, general manager for Calleguas. "We'd like to make this as equitable as possible."

Southern California Water's new rates will offset a 19% price increase that MWD passed on to its suppliers in 1993. It applied to the PUC for the increase in May and had hoped for approval by the time MWD's rate hike went into effect in July.

The lag was caused by delays in getting approval from the PUC, Dell'Osa said. As a private company, Southern California Water must gain the commission's approval for any rate increases.

Mohsen Kazemzadeh, PUC associate engineer, said calculation mistakes in the company's application contributed to the delay.

"They made some errors," he said. "It went back and forth a few times, so it took awhile to get it done."

The company may have to apply for another increase in May if Calleguas raises its rates in response to MWD's price hike earlier this month, Dell'Osa said.

Simi Valley Water District No. 8, a city-owned company that provides water to the rest of the area, may also increase its rates if Calleguas' prices go up, district engineer Michael Kleinbrodt said.

Water rates for residents supplied by District 8 are about the same as those charged by Southern California Water, Kleinbrodt said.